1. Field of the Invention
This invention relates to a magneto-optical recording medium such as a magneto-optical disk which is used for a large-capacity information file or the like. This invention particularly relates to an improvement of a magneto-optical recording layer of the magneto-optical recording medium.
2. Description of the Prior Art
Among optical recording media having various advantages, for example, the advantages that they can record information at a high density, have a large capacity, and need not be contacted with a read/write head, magneto-optical recording media have attracted attention from the viewpoint of easy erasing and rerecording.
The magneto-optical recording medium is composed of a magnetic material as a recording medium, and records information based on changes in magnetization of the magnetic material. For example, an amorphous alloy composed of a combination of a rare earth metal (RE) such as Gd, Tb or Dy with a transition metal such as Fe, Co or Ni is used as the magnetic material. The magnetic material is used in a layer form as a recording layer.
The rare earth metal used as the magnetic material is readily oxidized and corroded. When the magnetic material is oxidized or corroded, magnetic characteristics such as coercive force thereof deteriorate and it becomes not always possible to efficiently achieve magneto-optical recording. Therefore, in order to put the magneto-optical recording medium into practice, it is necessary to prevent oxidation and corrosion of the magnetic material.
In order to solve the aforesaid problem, it has been proposed in an article "Prolongation of Service Life of Photomagnetic Disk by Addition Element" by Shinsuke Tanaka (KDD Research Institute) et al. in the synopsis of science lecture meeting No. 9 of the Magnetics Society of Japan, p. 209, to make a magneto-optical recording medium wherein an addition element such as Pt capable of preventing oxidation and corrosion of the magnetic material is approximately uniformly contained in the recording layer.
However, with the proposed magneto-optical recording medium, since the addition element is approximately uniformly mixed with the magnetic material, the addition element and the magnetic material are intimately related to each other, and there is the risk of magnetic characteristics being deteriorated by the presence of the addition element.